1. Field of the Invention
The present invention relates to protective coatings for thin films of metals such as silver, a combination of silver and copper, or the like. More specifically, the present invention relates to protective compositions for mirror-backings comprising thin films of silver and copper, or silver only.
2. Brief Description of the Prior Art
It is known in the art to deposit thin metallic films on substrates for functional and/or aesthetic reasons. For example, thin films of silver are deposited on glass to produce mirrors or other reflective surfaces for purposes such as energy conservation. To preserve the integrity of the thin metallic films, additives, pertinent among which are corrosion inhibitors, are employed therewith. Typical examples of the corrosion inhibitors are lead compounds.
While the lead compounds provide good corrosion inhibition, they have become less desirable because of associated problems of toxicity. Hence, it has become necessary to find alternate or supplemental corrosion inhibitors that are helpful in preserving the integrity of the thin metallic films. The present invention provides such an alternate means of effecting the reduction or prevention of corrosion of thin metallic films.